Dry-pipe and pre-action sprinkler systems employ sprinkler distribution piping downstream from an automatic, normally closed, valve. This distribution piping is kept free of water, for example by using a compressed gas such as air, until a fire condition exists, whereupon the valve is opened thereby flooding the distribution piping. As opposed to dry-pipe systems which rely solely on the actuation of an automatic sprinkler head to release water into the piping system, pre-action systems use a separate fire detection system to control the release of water into the distribution piping system. Two principle types of pre-action fire sprinkler systems are currently in use, namely single interlock and double interlock systems. Both such interlocked pre-action fire sprinkler systems comprise a water distribution system, having water supply and distribution piping to which fire sprinklers are connected, and a separate detection system, which may include a plurality of smoke detectors for example. Pre-action systems therefore require a supplemental detection system, which may include a plurality of smoke detectors for example, that is distinct from the water distribution system and provided in the same area as the sprinkler system.
A deluge or pre-action valve, which is integrated into the water distribution piping system, is operated depending upon activation of a smoke detector or activation of both a smoke detector and a sprinkler.
Single interlock pre-action systems only require a smoke detector to operate in order to cause the deluge valve to open, thereby flooding the piping system with water. However, water will only be discharged from the sprinkler heads when a sprinkler operates (i.e. opens) due to the heat of the fire. Double interlock pre-action systems, however, require that both a smoke detector and a sprinkler to operate (i.e. indicate the presence of smoke and fire/heat, respectively) before causing the deluge valve to open thus flooding the distribution piping system with water.
Therefore, known pre-action fire sprinkler systems include a separate water supply system and a detection system. The water supply system includes a water distribution piping network to which automatic fire sprinklers are fluidly connected. The detection system includes one or more smoke detectors that are in communication with at least a deluge valve of the water supply system. The sprinkler system is connected to a pressurized water source via the deluge valve which, when opened, allows water to flow into the piping system.
As noted above, in single-interlock pre-action systems, the deluge valve is actuated when a fire detection event occurs, e.g. the detection of smoke by a smoke detector, in order to allow water to flood the piping system and thereby flow up to the automatic fire sprinklers. In double-interlock pre-action fire sprinkler systems, actuation of at least one fire sprinkler is further required, in addition to the actuation of a smoke detector, before the deluge valve is allowed to open such as to allow water to enter into the piping system.
While being efficient, such pre-action fire sprinklers typically require a large number of smoke detectors positioned adjacent to the automatic fire sprinklers, which increases the cost and complexity of the system. Further, in double interlock systems, a pressurized gas is typically required in the piping system prior to opening of the valve in order to ensure any opening of a fire sprinkler can be detected, however the presence of such a pressurized gas in the sprinkler pipes causes a significant delay in the delivery of water to the opened sprinklers, which can lead to more expensive installations and/or less optimal response times, etc.
Therefore, there is a need for an improved fire sprinkler system.